Trailer bodies are typically provided with a pair of side-by-side swing doors for closing an open end of the trailer body. Each swing door is pivotally interconnected to the trailer body by a plurality of vertically spaced hinges. Each hinge is configured to permit the swing door to move through an arc of about 270.degree.. The door to which the hinge is connected is typically formed from wood with steel or aluminum sheeting covering the inner and outer sides or surfaces thereof
As is well known, a series of attachment members, i.e., threaded bolts and nuts, are used to secure each hinge to a swing door. Because they are secured outside the trailer body and door, the hinges are exposed to all environmental conditions such as rain, sleet, snow as well as road salts, greases, dust, dirt and related debris which is thrown rearwardly as the trailer body moves over the road. Manufacturing costs and exposure to such environmental conditions has led many manufacturers to form the hinge assembly from aluminum. Besides its ability to withstand rust and corrosion, aluminum hinges are lightweight and yet offer significant strength.
A typical hinge assembly includes an elongated hinge plate having a mounting portion and a hinge portion. The mounting portion has a generally flat configuration and, as mentioned, is typically secured to the swing door of the trailer body. The hinge portion of the hinge plate typically fits between vertically spaced and axially aligned apertured projections of a hinge butt. Moreover, the hinge portion of the hinge plate defines an elongated passage or opening for accommodating a steel pivot member. As will be appreciated, the steel pivot member passes endwise through an aperture defined by the upper projection of the hinge butt, downwardly through the elongated passage defined by the hinge portion of the hinge plate, and, ultimately, through the aperture on the lower projection of the hinge butt. During swinging movements of the door, the inner diameter or margin of the elongated passage defined by the hinge portion of the hinge plate rotates on the steel pivot member. Steel or nylon washers are commonly provided between upper and lower surfaces of the hinge portion of the hinge plate and the projections on the hinge butt. These washers are free to rotate relative to the pivot member and to the hinge plate.
Although generally beneficial to hinge performance, using washers in combination with the hinges presents certain problems. Such problems are furthermore exacerbated when the hinge plate is formed from aluminum. Many times the washers catch on or are frozen to the hinge butt, and remain stationary with the hinge butt as the door swings between open and closed positions. In such an instance, during rotation of the hinge, the ends of the hinge portion of the hinge plate rub against the washers. Whether the washer is made from steel or nylon, the softer aluminum on the hinge plate wears. As will be appreciated by those skilled in the art, wearing of the hinge portion of the hinge plate can result in the door sagging and, thus, presenting a myriad of additional problems.
The use of washers in combination with the hinge furthermore complicates the installation process. During installation, the pivot member must pass through the hole or aperture in one end of the hinge butt, through a washer, through the elongated opening in the hinge portion of the hinge plate, through a second washer, and, ultimately through the other hole or aperture at the opposite end of the hinge butt. As will be appreciated, difficulties arise in lining up all the holes while maintaining the relatively small washers in place as the pivot member is being inserted through the various components of the hinge assembly.
In some aluminum hinges, bearings are press fit into the elongated passage defined by the hinge plate. As will be appreciated by those skilled in the art, such bearings must be press fit into the hinge plate or the tolerances between the parts would result in an unacceptable product. In such heretofore known aluminum hinges, and because of the press fit established between the bearings and the hinge plate, it is substantially impossible to replace the bearings when they wear. Instead, the entire hinge plate with the bearings pressed thereinto must be replaced. In addition to the cost of the bearings, providing such bearings in combination with the hinge plate involves a labor intensive operation along with appropriate tooling costs, thus, leading to a relatively expensive hinge assembly. Of course, the cost of each hinge assembly is multiplied by the number of hinges used to interconnect the door to the trailer body.
Thus, there is a continuing need and desire for a hinge assembly utilizing an economic aluminum hinge plate provided with bearings to enhance the wearability of the hinge assembly over an extended period of time.